MovementSystem.cs

using Unity.Burst;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;

namespace HelloCube.CustomTransforms
{
    public partial struct MovementSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<LocalTransform2D>();
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            float rotation = SystemAPI.Time.DeltaTime * 180f; // Half a rotation every second (in degrees)
            float elapsedTime = (float) SystemAPI.Time.ElapsedTime;
            float xPosition = math.sin(elapsedTime) * 2f - 1f;
            float scale = math.sin(elapsedTime * 2f) + 1f;
            scale = scale <= 0.001f ? 0f : scale;

            foreach (var localTransform2D in
                     SystemAPI.Query<RefRW<LocalTransform2D>>()
                         .WithNone<Parent>())
            {
                localTransform2D.ValueRW.Position.x = xPosition;
                localTransform2D.ValueRW.Rotation = localTransform2D.ValueRO.Rotation + rotation;
                localTransform2D.ValueRW.Scale = scale;
            }
        }
    }
}